System and method for message queue management in a power-save network

ABSTRACT

A method and apparatus for communicating information between networked devices. Various aspects of the present invention may comprise, for example, a first networked device communicating information over a wireless communication network to a second networked device having power-save mode capability. The first networked device receives an incoming message from the second networked device. A first outgoing message is transmitted to the second networked device prior to transmitting a previously queued outgoing message. A second outgoing message is transmitted to the second networked device prior to the previously queued outgoing message being transmitted. Information may be communicated to the second networked device in a particular manner that depends on whether the second networked device has power-save capability. Communication medium access may be performed in a particular manner, depending on whether the second networked device has power-save capability.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This patent application claims the benefit of U.S. ProvisionalApplication No. 60/501,781, filed Sep. 10, 2003, titled “SYSTEM ANDMETHOD FOR POWER MANAGEMENT IN A WIRELESS NETWORK,” the contents ofwhich are hereby incorporated herein by reference in their entirety.This patent application is related to U.S. patent application, attorneydocket number 15186US02, filed concurrently with the present patentapplication, titled “SYSTEM AND METHOD FOR MEDIUM ACCESS CONTROL IN APOWER-SAVE NETWORK.”

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[Not Applicable]

SEQUENCE LISTING

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MICROFICHE/COPYRIGHT REFERENCE

[Not Applicable]

FIELD OF THE INVENTION

The present invention relates generally to message queue management.More specifically, the present invention relates to method and apparatusfor managing and utilizing a message queue in a power-save network.

BACKGROUND OF THE INVENTION

Modern communication networks include a vast array of device types. Suchdevice types may include, for example, wired and wireless devices, andstationary and portable devices. Some networked devices may haverelatively limitless electrical power supplies, for example, thosedrawing electrical power from wall outlets. Conversely, some networkeddevices may have limited power supplies, for example, those operating oninternal batteries.

Networked devices operating with limited power supplies may adoptoperating characteristics that are conducive to conserving their limitedsupplies of power. For example, some devices may have an operating mode,sometimes called a “sleep mode” or “power-save mode,” where the deviceshuts down or slows down many of its internal functions to conserveenergy. Such functions may include, for example, network communicationfunctionality. Such devices may, for example, periodically or on-commandexit the power-save mode and re-establish communications with othernetworked devices.

For example, a remote network device in power-save mode may exit thepower-save mode and establish communications with a communicationnetwork access point. Once such communications are established, theexemplary remote network device and network access point may exchangeinformation. For example, the remote device may transmit information tothe access point that is destined for another networked device, and theaccess point may transmit information to the remote device that theaccess point had buffered for the remote device while the remote devicewas in power-save mode and unable to communicate with the access point.

The process of communicating information between the exemplary remotedevice and network access point, and between devices in general,consumes energy. The process of merely monitoring the network whilewaiting for the arrival of a packet also consumes energy. Communicationnetworks are generally governed by various communication procedures andprotocols that control various communication functions. Such functionsmay include, for example, access to the communication medium and messagequeuing. Such medium access protocols, message queuing procedures, andother rules or procedures governing information transfer typicallyinclude aspects that are inefficient with regard to, for example, energyconsumption, information transfer speed, and bandwidth utilization.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with the present invention as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

Various aspects of the present invention provide a method and apparatusfor communicating information between networked devices in acommunication network. Various aspects of the present invention maycomprise, for example, a first networked device communicatinginformation over a wireless communication network to a second networkeddevice having power-save capability. The first and second networkeddevices may each include, for example, respective communication modules.

Various aspects of the present invention may comprise the firstnetworked device receiving an incoming message from the second networkeddevice. The incoming message may, for example, indicate that the secondnetworked device is not presently operating in a power-save mode and/oris ready to receive information. The incoming message may, for example,be a control message. The incoming message may, for example, be a datamessage comprising an indication that the second networked device has nomore information to transmit to the first networked device.

Various aspects of the present invention may comprise transmitting afirst outgoing message to the second networked device prior totransmitting a previously queued outgoing message. The first outgoingmessage may be, for example, a data message or a control message.Various aspects may comprise waiting for a second incoming message aftertransmitting the first outgoing message. A second outgoing message maybe transmitted to the second networked device prior to transmitting thepreviously queued outgoing message.

Various aspects of the present invention may comprise determiningwhether the second networked device has power-save capability. Suchdetermination may, for example, comprise analyzing information in adatabase to determine if the second networked device has power-savecapability. Information may be communicated to the second networkeddevice in a first manner if the second networked device has power-savecapability and in a second manner if the second networked device doesnot have power-save capability.

Various aspects of the present invention may comprise accessing thenetwork communication medium in a particular manner, depending onwhether the second networked device has power-save capability. Suchmedium access may, for example, comprise taking control over thecommunication medium without contending with other networked devices foraccess to the communication medium. Access to the communication mediummay be limited to, for example, a maximum time limit for a particularmessage exchange sequence.

These and other advantages, aspects and novel features of the presentinvention, as well as details of illustrative aspects thereof, will bemore fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a flow diagram of a method for communicating informationfrom a first networked device having an outgoing message queue to asecond networked device in accordance with various aspects of thepresent invention.

FIG. 2 shows a flow diagram of a method for communicating informationfrom a first networked device having an outgoing message queue to asecond networked device having power-save capability in accordance withvarious aspects of the present invention.

FIG. 3 illustrates a first exemplary message exchange between twonetworked devices in accordance with various aspects of the presentinvention.

FIG. 4 illustrates a second exemplary message exchange between twonetworked devices in accordance with various aspects of the presentinvention.

FIG. 5 shows a block diagram of a communication system utilizing acommunication module for communicating information from a firstnetworked device to a second networked device in accordance with variousaspects of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a flow diagram of a method 100 for communicatinginformation from a first networked device having an outgoing messagequeue to a second networked device in accordance with various aspects ofthe present invention. The method 100 may, for example, be implementedin a first networked device in a communication network. Such acommunication network may, for example, be a wireless communicationnetwork. The first networked device may have a queue for outgoingmessages that are to be transmitted over the communication network.

The method 100 includes, at step 110, receiving an incoming message froma second networked device. The second networked device may, for example,be a device having power-save capability that is communicatively coupledto the first networked device over the communication network. Theincoming message may, for example, indicate that the second networkeddevice is ready to receive information from the first networked device.If the second networked device is capable of power-save operation (e.g.,capable of entering and exiting an operating mode in which the deviceconsumes a relatively low amount of energy), the incoming message may,for example, indicate that the second networked device is not currentlyin a sleeping state of a power-save mode. Note that various aspects ofthe present invention should not be limited to methods and apparatusassociated with power-save devices.

The incoming message may assume a variety of forms, including, but notlimited to, a data message and a control message. The incoming messagemay, for example, be a data message including an indication that thesecond networked device has no data, or no more data, to send to thefirst networked device. Accordingly, the scope of various aspects of thepresent invention should not be limited to the form of the incomingmessage.

The method 100, at step 120, includes determining if the first networkeddevice has a message for delivery to the second networked device. Thefirst networked device may, for example, include a message buffer inwhich the first networked device stores outgoing messages destined forother networked devices. For example, in a communication network havingnetworked devices capable of power-save operation, the first networkeddevice may buffer outgoing messages that are addressed to the secondnetworked device. The first networked device may buffer such messages,for example, until the first networked device receives an indicationthat the second networked device, while operating in power-save mode, isnot currently in a sleeping state.

If step 120 determines that the first networked device does not have anoutgoing message to send to the second networked device, the method 100flow may end, at which time the operation of the first networked devicemay, for example, return to the mode of operation at which the firstnetworked device was operating when the incoming message arrived.Conversely, if step 120 determines that the first networked device hasan outgoing message to send to the second networked device, the method100 flow may continue to step 130.

The method 100, at step 130, includes bypassing the outgoing messagequeue to transmit, at step 140, the outgoing message to the secondnetworked device. For example, when the first networked device receivedthe incoming message, the first networked device may have had one ormore outgoing messages in an outgoing message queue waiting fortransmission. Rather than placing the buffered outgoing message destinedfor the second networked device in the non-buffered outgoing messagequeue to wait in line behind the messages already queued in the outgoingmessage queue, step 130 includes by-passing one or more messages in thenon-buffered outgoing message queue. Thus, step 130 provides for theoutgoing message destined for the second networked device to bedelivered to the second networked device in a timely manner.

An exemplary advantage provided by step 130 is that in a power-savescenario where the second networked device has emerged from a power-savemode to communicate with the first networked device, the secondnetworked device may complete its communications with the firstnetworked device and return to the sleeping state of the power-save modein a time-efficient manner, thereby reducing unnecessary energyconsumption by the second networked device.

The outgoing message transmitted to the second networked device may takevarious forms. For example, in a scenario where the first networkeddevice is able to retrieve a buffered message destined for the secondnetworked device quickly enough to meet communication system timingconstraints, the outgoing message may include the buffered message. Inan alternative example, the first networked device may not be able toretrieve a buffered message destined for the second networked devicequickly enough to meet communication system timing constraints. In sucha scenario, the first networked device may communicate a message (e.g.,a null data message) to the second networked device. Such a message may,for example, provide for maintaining control over the communicationmedium and may also serve as an indication to the second networkeddevice that a message or stream of message is forthcoming from the firstnetworked device. Note that the scope of various aspects of the presentinvention should not be limited to a particular form of outgoingmessage.

After transmitting a first outgoing message to the second networkeddevice at step 140, the method 100, at step 150, determines if the firstnetworked device has an additional message buffered that is destined forthe second networked device. If step 150 determines that the firstnetworked device has no more messages for the second networked device,the method 100 flow may end, at which time the operation of the firstnetworked device may, for example, return to the operational state inwhich the first networked device was operating when the incoming messagearrived.

Conversely, if step 150 determines that the first networked device hasan additional outgoing message to send to the second networked device,the method 100 flow may loop back to step 130. Having looped back tostep 130, the method 100 flow may repeat steps 130, 140 and 150 untilthe first networked device has no more outgoing messages buffered forthe second networked device.

The method 100 illustrated in FIG. 1 shows various aspects of a methodfor communicating information from a first networked device to a secondnetworked device. Refer now to FIG. 2 for an exemplary illustration ofadditional aspects of the present invention.

FIG. 2 shows a flow diagram of a method 200 for communicatinginformation from a first networked device having an outgoing messagequeue to a second networked device having power-save capability inaccordance with various aspects of the present invention. The method 200may, for example, be implemented in a first networked device in acommunication network. Such a communication network may, for example, bea wireless communication network. The first networked device may have aqueue for outgoing messages that are waiting to be transmitted over thecommunication network.

The method 200 includes, at step 210, receiving an incoming message froma second networked device. The second networked device may, for example,be a device having power-save capability that is communicatively coupledto the first networked device over the communication network. In anexemplary scenario, the second networked device may have awakened from asleeping state of a power-save mode, acquired access to thecommunication medium using a contention-based medium access protocol(e.g., CSMA/CA), and sent the incoming message to the second networkeddevice. In an exemplary scenario, the first networked device may be anaccess point in a wireless communication network.

The incoming message may, for example, indicate that the secondnetworked device is ready to receive information from the firstnetworked device, such as is shown in step 215. If the second networkeddevice is capable of power-save operation (e.g., capable of entering andexiting an operating state in which the device consumes a relatively lowamount of energy), the incoming message may, for example, indicate thatthe second networked device is not currently operating in anon-communicative state of the power-save mode. Note that variousaspects of the present invention should not be limited to methods andapparatus associated with power-save devices.

The incoming message may assume a variety of forms, including, but notlimited to, a data message and a control message. The incoming messagemay, for example, be a data message including an indication that thesecond networked device has no data, or no more data, to send to thefirst networked device. Accordingly, the scope of various aspects of thepresent invention should not be limited to the form of the incomingmessage.

The method 200, at step 220, may include determining if the secondnetworked device is operating in a power-save mode and/or whether thesecond networked device is currently operating in a sleep state of apower-save mode. The second networked device may, for example, becapable of operating in a “normal mode” and a “power-save mode” in whichthe first networked device may effectively shut down many operatingfunctions for a time period to save energy. Such an exemplary secondnetworked device may, for example, operate in a power-save mode,sometimes operating in a sleeping state and occasionally waking to anactive state to communicate with a network access point to determine ifthe access point has buffered messages addressed to the second networkeddevice.

Step 220 may, for example, determine if the second networked device isoperating in the power-save mode, and/or a sleep state of a power-savemode, by analyzing the incoming message for an indication that thesecond networked device is capable of such operation and has enabledsuch operational mode. Alternatively, for example, step 220 may includeanalyzing a database of networked device information to determine if thedatabase indicates that the second networked device is capable ofpower-save mode operation and has enabled its power-save mode ofoperation or a sleep state thereof. For example, when the secondnetworked device entered the communication network, the second networkeddevice may have registered with the network, providing operatingcapability information, such as whether the device is power-savecapable. Also, for example, the second networked device may communicateits current state of power-save operation in a variety of ways.

If step 220 determines that the second networked device is not apower-save device or, for example, the second networked device is apower-save device that is currently in a sleep state, the exemplarymethod 200 flow may end, at which time the operation of the firstnetworked device may, for example, return to the mode of operation atwhich the first networked device was operating when the incoming messagearrived. Conversely, for example, if step 220 determines that the secondnetworked device is a power-save device and is currently not operatingin a sleep state, the method 200 flow may continue to step 230. Althoughthe illustrative exemplary method 200 includes special accommodationsfor power-save devices, and the method 200 may include communicatingwith power-save devices differently than non-power-save devices, thescope of various aspects of the present invention should not be limitedby such exemplary operation.

The method 200, at step 230, includes determining if the first networkeddevice has a message for delivery to the second networked device. Thefirst networked device may, for example, include a message buffer inwhich the first networked device stores outgoing messages destined forother networked devices. For example, in a communication network havingnetworked devices capable of power-save operation, the first networkeddevice may buffer outgoing messages that are addressed to the secondnetworked device. The first networked device may buffer such messages,for example, until the first networked device receives an indicationthat the second networked device is not currently operating in apower-save mode and/or until the first networked device receives anindication that the second networked device is not currently operatingin a sleeping state.

If step 230 determines that the first networked device does not have anoutgoing message to send to the second networked device, the method 200flow may end, at which time the operation of the first networked devicemay, for example, return to the mode of operation at which the firstnetworked device was operating when the incoming message arrived.Conversely, if step 230 determines that the first networked device hasan outgoing message to send to the second networked device, the method200 flow may continue to step 240.

The method 200, at step 240, having determined that the first networkeddevice has an outgoing message to communicate to the second networkeddevice, determines if there is enough time to communicate the outgoingmessage to the second networked device and maintain operation within thetiming constraints of the communication network. For example, thecommunication network may have a maximum time limit for which one orboth of the first and second networked devices may utilize thecommunication medium before allowing other networked devices anopportunity to access the communication medium.

In such an exemplary situation, step 240 may determine how long it willtake to communicate the outgoing message to the second networked device.Such a time determination may include, for example, determining how longit will take the first networked device to transmit the outgoing messageto the second networked device and how long it will take the secondnetworked device to return an acknowledgement message to the firstnetworked device. Having determined the communication time, the firstnetworked device may compare the communication time to how much time thefirst networked device has left for utilizing the communication mediumbefore system timing constraints require the first and/or secondnetworked devices to release control of the communication medium forpotential utilization by other networked devices.

If step 240 determines that there is not time under the system timeconstraints to effectively communicate the outgoing message to thesecond networked device, the exemplary method 200 flow may end, at whichtime the operation of the first networked device may, for example,return to the mode of operation at which the first networked device wasoperating when the incoming message arrived. Conversely, if step 240determines that the first networked device has time to effectivelycommunicate the outgoing message to the second networked device, themethod 200 flow may continue to step 250.

The method, at step 250, includes bypassing the process of contendingfor access to the communication medium to communicate the outgoingmessage to the second networked device. For example, in an exemplaryscenario, the second networked device may have awakened from a sleepingstate of the power-save mode and gained access to the communicationmedium using a contention-based medium access protocol, such as, forexample CSMA/CA. Having contended with other networked devices foraccess to the communication medium, and having acquired control of thecommunication medium, the second networked device may then havetransmitted the incoming message to the first networked device.

The first networked device, having determined at step 220 that thesecond networked device is a power-save device, and having determined atstep 230 that the first networked device has a message for thepower-save device, may, for example, at step 250 utilize thecommunication medium to communicate the outgoing message to the secondnetworked device without contending with other networked devices foraccess to the communication medium. Such operation may provide forcommunicating one or more outgoing messages to the second networkeddevice in a time-efficient, and thus energy-efficient, manner. Note thatsuch medium access operation is exemplary and should, by no means, limitthe scope of various aspects of the present invention to particularmedium access protocols.

The method 200, at step 260, includes bypassing the outgoing messagequeue to transmit, at step 270, the outgoing message to the secondnetworked device. For example, when the first networked device receivedthe incoming message, the first networked device may have had one ormore outgoing messages in an outgoing message queue waiting fortransmission. Rather than placing the outgoing message destined for thesecond networked device in the outgoing message queue to wait in linebehind the messages already queued in the outgoing message queue, step260 includes by-passing one or more messages in the outgoing messagequeue. Thus, step 260 provides for the outgoing message destined for thesecond networked device to be delivered to the second networked devicein a time-efficient manner.

An exemplary advantage provided by step 260 is that in a power-savescenario where the second networked device has emerged from a power-savemode to communicate with the first networked device, the secondnetworked device may complete its communications with the firstnetworked device and return to the power-save mode in a time-efficientmanner, thereby reducing unnecessary energy consumption by the secondnetworked device.

The outgoing message transmitted to the second networked device may takevarious forms. For example, in a scenario where the first networkeddevice is able to retrieve a buffered message addressed to the secondnetworked device quickly enough to meet communication system timingconstraints, the outgoing message may include the buffered message. Inan alternative example, the first networked device may not be able toretrieve a buffered message addressed to the second networked devicequickly enough to meet communication system timing constraints. In sucha scenario, the first networked device may communicate an alternativemessage (e.g., a null data message) to the second networked device. Sucha message may, for example, provide for maintaining control over thecommunication medium and may also serve as an indication to the secondnetworked device that a message or stream of messages is forthcomingfrom the first networked device. Note that the scope of various aspectsof the present invention should not be limited to a particular form ofoutgoing message.

After transmitting a first outgoing message to the second networkeddevice at step 270, the method, at step 280, may include waiting for asecond incoming message from the second networked device. For example,such a second incoming message may include an acknowledgment from thesecond networked device that the second networked device received themost recent message transmitted to the second networked device at step270. The second incoming message may, for example, also include arequest from the second networked device for the first networked deviceto retransmit a message. The first networked device may, for example,respond to such a request, or the absence of a response message, byretransmitting the outgoing message to the second networked device.

After transmitting a first outgoing message to the second networkeddevice at step 270, and optionally waiting for a second incoming messageat step 280, the method 200, at step 290, determines if the firstnetworked device has an additional message buffered that is addressed tothe second networked device. If step 290 determines that the firstnetworked device has no more messages for the second networked device,the method 200 flow may end, at which time the operation of the firstnetworked device may, for example, return to the mode of operation atwhich the first networked device was operating when the incoming messagearrived.

Conversely, if step 290 determines that the first networked device hasan additional outgoing message to send to the second networked device,the method 200 flow may loop back to step 240. Having looped back tostep 240, the method 200 flow may repeat steps 240-290 until the firstnetworked device has no more outgoing messages buffered for the secondnetworked device or until system timing constraints require the firstand/or second networked devices to release control of the communicationmedium for potential utilization by other networked devices.

The methods 100 and 200 illustrated in FIGS. 1 and 2 show variousaspects of exemplary methods for communicating information between afirst networked device and a second networked device. Refer now to FIGS.3 and 4 for exemplary applications of portions of the methods 100, 200to an IEEE 802.11 communication environment.

FIG. 3 illustrates a first exemplary message exchange 300 between twonetworked devices in accordance with various aspects of the presentinvention. As explained above, the exemplary message exchange 300 isprovided in the context of the IEEE 802.11 standard. However, by nomeans, should the scope of various aspects of the present invention belimited to IEEE 802.11 features and implementations.

The bottom row of the message exchange 300 is labeled “QAP.” Thisgenerally refers to a quality of service access point in the IEEE 802.11context. The QAP may be generally thought of, for this example, as afirst networked device. The top row of the message exchange 300 islabeled “QSTA.” This generally refers to a quality of service station inthe IEEE 802.11 context. The QSTA may be generally thought of, for thisexample, as a second networked device that may have power-savecapabilities.

Prior to the exemplary message exchange 300, the QSTA gains access toand control of the communication medium. For example, the QSTA mayacquire access to the communication medium following a contention-basedmedium access protocol, such as, for example CSMA/CA.

The message (or packet) exchange 300 begins with a first message 310sent from the QSTA to the QAP. The first message 310 may, for example,be a Q-Data message with the “More” flag set. Such an exemplary firstmessage 310 may communicate data to the QAP and also indicate to theQAP, in a power-save scenario, that the QSTA is not currently operatingin the sleep state of the power-save mode.

Following an inter-frame spacing interval (SIFS), the message exchange300 includes the QAP sending a second message 320 to the QSTA. Thesecond message 320 may, for example, be an acknowledgement message (ACK)to indicate to the QSTA that the QAP successfully received the firstmessage 310.

The message exchange 300 then includes a third message 330 from the QSTAto the QAP. The third message 330 may, for example, be a Q-Data messagewith the “More” flag unset. The unset “More” flag may indicate to theQAP that the QSTA has no more data to send to the QAP. The unset “More”flag may also, for example, indicate to the QAP that the QSTA isstanding by to receive information from the QAP that the QAP may havebuffered for the QSTA while the QSTA was operating in the sleep state ofthe power-save mode.

As discussed previously, the QAP, at this point, may treat power-savedevices differently than non-power-save devices. For example, if the QAPdetermines that the QSTA is not a power-save device, the QAP may, forexample, merely acknowledge receipt of the third message 330 and ceasecommunicating with the QSTA, returning to the mode of operation at whichthe QAP was operating when it received the first message 310.Conversely, if the QAP determines that the QSTA is a power-save device,the QAP may, for example, enter an operating mode for communicatingbuffered information to power-save devices.

At this point in the exemplary message exchange 300, the QAP may, forexample, assume control over the communication medium. The QAP, upondetermining that the QAP has a message (or information) buffered for theQSTA, and upon determining that there is time within the system timeconstraints to communicate the message to the QSTA, responds by sendinga fourth message 340 to the QSTA. The fourth message 340 may, forexample, be a Q-Data message that includes data for the QSTA and anindication acknowledging receipt of the third message 330. The exemplaryQAP, having an outgoing message queue for outgoing messages, may bypassthe outgoing message queue with the fourth message 340, therebydelivering the fourth message 340 to the QSTA in a time-efficientmanner.

The exemplary message exchange 300 then includes a fifth message 350from the QSTA to the QAP, which may, for example, acknowledge receipt ofthe fourth message 340 by the QSTA. The message exchange 300 then, uponthe QAP determining that the QAP has an additional message (orinformation) buffered for the QSTA, and upon determining that there istime within the system time constraints to communicate the message tothe QSTA, includes a sixth message 360 from the QAP to the QSTA, whichmay, for example, include additional data for the QSTA. The exemplaryQAP, having an outgoing message queue for outgoing messages, may bypassthe outgoing message queue with the sixth message 360, therebydelivering the sixth message 360 to the QSTA in a time-efficient manner.

The message exchange 300 then includes a seventh message 370 from theQSTA to the QAP, which may, for example, include an indicationacknowledging receipt of the sixth message 360 by the QSTA.

The exemplary message exchange 300 may continue with the QSTA and theQAP exchanging information, for example, until the QAP exhausts itssupply of information to be communicated to the QSTA. Alternatively, forexample, the QSTA and QAP may discontinue the message exchange 300 dueto expiration of a system time limit on medium access.

FIG. 4 illustrates a second exemplary message exchange 400 between twonetworked devices in accordance with various aspects of the presentinvention. As with the exemplary message exchange 300 illustrated inFIG. 3, the second exemplary message exchange 400 is provided in thecontext of the IEEE 802.11 standard. However, by no means, should thescope of various aspects of the present invention be limited to IEEE802.11 features and implementations.

The bottom row of the message exchange 400 is labeled “QAP.” Thisgenerally refers to a quality of service access point in the IEEE 802.11context. The QAP may be generally thought of, for this example, as afirst networked device. The top row of the message exchange 400 islabeled “QSTA.” This generally refers to a quality of service station inthe IEEE 802.11 context. The QSTA may be generally thought of, for thisexample, as a second networked device that may have power-savecapabilities.

Prior to the exemplary message exchange 400, the QSTA gains access toand control of the communication medium. For example, the QSTA mayacquire access to the communication medium following a contention-basedmedium access protocol, such as CSMA/CA.

The exemplary message (or packet) exchange 400 begins with a firstmessage 410 sent from the QSTA to the QAP. The first message 410 may,for example, be a Q-Data message with the “More” flag unset. Such afirst message 410 may, for example, indicate to the QAP in a power-savescenario that the QSTA is not currently operating in a power-save modeand is standing by to receive traffic that the QAP may have beenbuffering for the QSTA while the QSTA was in a power-save mode. Theunset “More” flag may also, for example, indicate to the QAP that theQAP may assume control over the communication medium withoutinterference from the QSTA.

As discussed previously, the QAP, at this point, may treat power-savedevices differently than non-power-save devices. For example, if the QAPdetermines that the QSTA is not a power-save device, the QAP may merelyacknowledge receipt of the first message 410 and cease communicatingwith the QSTA, thereby releasing the communication medium and returningto the operating mode at which the QAP was operating when it receivedthe first message 410. Conversely, if the QAP determines that the QSTAis a power-save device, the QAP may, for example, enter a specialoperating mode for communicating buffered information to power-savedevices.

At this point in the exemplary message exchange 400, the exemplary QAPassumes control over the communication medium. The QAP, upon determiningthat the QAP has a message (or information) buffered for the QSTA, andupon determining that there is time within the system time constraintsto communicate the message to the QSTA, responds by sending a secondmessage 420 to the QSTA. The second message 420 may, for example, be aQ-Data message that includes data for the QSTA and an indicationacknowledging receipt of the first message 410. The exemplary QAP,having an outgoing message queue for outgoing messages, may bypass theoutgoing message queue with the second message 420, thereby deliveringthe second message 420 to the QSTA in a time-efficient manner.

Additionally, for example, the second message 420 may include a nulldata frame, which may indicate to the QSTA that the QAP has informationtraffic buffered for delivery to the QSTA, but that the QAP needsadditional time to acquire the information from the buffer. Such a nulldata frame may, for example, allow the QAP to retain control of thecommunication medium (e.g., a communication medium controlled by acontention-based medium access control protocol) while the QAP isobtaining the information traffic destined for the QSTA.

The exemplary message exchange 400 then includes a third message 430from the QSTA to the QAP. The third message 430 may, for example,include an indication to acknowledge receipt of the second message 420by the QSTA.

The message exchange 400 then, upon the QAP determining that the QAP hasan additional message (or information) buffered for the QSTA, and upondetermining that there is time within the system time constraints tocommunicate the message to the QSTA, includes a fourth message 440 fromthe QAP to the QSTA, which may, for example, include additional data forthe QSTA. The exemplary QAP, having an outgoing message queue foroutgoing messages, may bypass the outgoing message queue with the fourthmessage 440, thereby delivering the fourth message 440 to the QSTA in atime-efficient manner.

The message exchange 400 then includes a fifth message 450 from the QSTAto the QAP, which may, for example, include an indication acknowledgingreceipt of the fourth message 440.

The message exchange 400 then, upon the QAP determining that the QAP hasan additional message (or information) buffered for the QSTA, and upondetermining that there is time within the system time constraints tocommunicate the message to the QSTA, includes a sixth message 460 fromthe QAP to the QSTA, which may, for example, include additional data forthe QSTA. The exemplary QAP, having an outgoing message queue foroutgoing messages, may bypass the outgoing message queue with the sixthmessage 460, thereby delivering the sixth message 460 to the QSTA in atime-efficient manner.

The message exchange 400 then includes a seventh message 470 from theQSTA to the QAP, which may, for example, include an indicationacknowledging receipt of the sixth message 460.

The exemplary message exchange 400 may continue with the QSTA and theQAP exchanging information, for example, until the QAP exhausts itssupply of information to be communicated to the QSTA. Alternatively, forexample, the QSTA and QAP may discontinue the message exchange 400 dueto expiration of a system time limit on medium access.

FIG. 5 shows a block diagram of a communicating system 500 utilizing acommunication module 520 for communicating information between a firstnetworked device and a second networked device 510 in accordance withvarious aspects of the present invention. The communication module 520may, for example, be utilized by a first networked device in acommunication network. For example and without limitation, the firstnetworked device may be an access point communicatively coupled to awired network 524 using a wired LAN module 522. The second networkeddevice 510 may, for example, be communicatively coupled to thecommunication module 520 over a wireless communication link.

The exemplary second networked device 510 includes a transceiver module512 for communicating over communication links to other networkeddevices. The second networked device 510 may include a MAC Module 518that governs access to the network communication medium. The secondnetworked device 520 may also include a data communication module 514that generally controls the flow of data between the second networkeddevice 510 and other networked devices. The second networked device 510may further include a power-save module 516 that provides the secondnetworked device 510 the capability to operate in a power-save mode asdiscussed previously. FIG. 5 shows the exemplary second networked device510 having various components for illustrative purposes only.Accordingly, the scope of various aspects of the present inventionshould, in no way, be limited to characteristics of the exemplary secondnetworked device 510.

The exemplary communication module 520 may include a transceiver module530 communicatively coupled to a data communication module 540. The datacommunication module 540 may be communicatively coupled to a messagebuffer 545 and an outgoing message queue 550. The communication module520 may, for example, also include a Medium Access Control (MAC) module580 communicatively coupled to the data communication module 540 and thetransceiver module 530. The MAC module 580, in turn, may include anaccess time limiting module 590 and an access module 585. Thecommunication module 520 may, for example, additionally include apower-save determination module 560 communicatively coupled to the datacommunication module 540 and a power-save information database 570. FIG.5 shows the exemplary communication module 520 having various componentsfor illustrative purposes only, and accordingly, in no way, should thevarious characteristics (e.g., sub-module boundaries, couplings andlocations) of the exemplary communication module 520 limit the scope ofvarious aspects of the present invention.

The transceiver module 530 is capable of receiving an incoming messagefrom the second networked device 510. As explained previously, thesecond networked device 510 may, for example, include a power-savemodule 516, providing the second networked device 510 with thecapability to operate in a power-save mode. Also as explainedpreviously, the second networked device 510 may, for example, include aMAC module 518 that gains access to and control of the networkcommunication medium utilizing a contention-based medium accessprotocol. The second networked device 510 may, for example, send anincoming message to the communication module 520 after exiting from thepower-save mode and gaining access to the communication medium using thecontention-based medium access protocol.

The incoming message may, for example, indicate to the communicationmodule 520 that the second networked device 510 is ready to receiveinformation from the communication module 520. If the second networkeddevice 510 is capable of power-save operation, the incoming message may,for example, indicate that the second networked device 510 is notcurrently in a power-save mode and/or is not currently in the sleepingstate of a power-save mode. Though various components of theillustrative communication system 500 may be related to networkeddevices having power-save capability, various aspects of the presentinvention should not be limited to methods and apparatus associated withsuch power-save devices.

The incoming message may assume a variety of forms, including, but notlimited to, a data message and a control message. The incoming messagemay, for example, be a data message including an indication that thesecond networked device 510 has no data, or no more data, to send to thecommunication module 520. Accordingly, the scope of various aspects ofthe present invention should not be limited to characteristics of theincoming message.

The communication module 520 includes a data communication module 540.The data communication module 540 may, for example, control the generalflow of information between the communication module 520 and othernetworked devices.

The communication module 520 includes a power-save determination module560, which may determine if the second networked device 510 is capableof operating in a power-save mode. The power-save determination module560 may additionally, for example, determine whether the secondnetworked device 510 is currently operating in a sleep state of apower-save mode. The exemplary power-save determination module 560 may,for example, analyze information in the power-save information database570 to determine whether the second networked device 510 is a power-savedevice. The exemplary power-save determination module 560 may also, forexample, analyze information in the power-save information database 570to determine whether the second networked device 510 is currentlyoperating in a sleep state of a power-save mode.

The power-save information database 570 may, for example, includeoperational information for devices in the communication network. Forexample, when a device enters the communication network, the device mayregister by providing operational capabilities. Alternatively, forexample, the power-save determination module 560 may analyze theincoming message to determine whether the second networked device 560 isa power-save device or whether the second networked device 560 iscurrently operating in a sleep state of a power-save mode. Accordingly,the scope of various aspects of the present invention should not belimited to a particular method or apparatus for determining thepower-save capability and state of a networked device.

The data communication module 540 may utilize the power-savedetermination module 560 to determine whether the second networkeddevice 510 is a power-save device or, for example, whether the secondnetworked device 510 is in a sleep state. If the power-savedetermination module 560 determines that the second networked device 510is not a power-save device, the data communication module 540 may, forexample, return to the mode of operation at which the data communicationmodule 540 was operating when the incoming message arrived. Conversely,if the power-save determination module 560 determines that the secondnetworked device 510 is a power-save device and is currently not in asleep state of a power-save mode, the data communication module 540 mayconduct communications with the second networked device 510 in a mannerconducive to the needs of such power-save devices. Note, however, thatcommunicating with networked devices in a different manner depending onwhether the networked devices are power-save devices is but oneexemplary operating characteristic of the communication module 520 andshould not limit the scope of various aspects of the present invention.

The data communication module 540 is communicatively coupled to themessage buffer 545. The communication module 520 or other modules in thefirst networked device may, for example, utilize the message buffer 545to store message information for delayed communication to othernetworked devices. For example, the communication module 520 may storemessage information in the message buffer 545 that is addressed tonetworked devices having power-save capability. The communication module520 may, for example, store such message information in the messagebuffer 545 until the communication module 520 receives an indicationthat the addressed networked device is not in the power-save mode and/ornot in the sleeping state of the power save mode and is therefore readyto receive the message information.

After receiving the incoming message from the second networked device510, the data communication module 540 may determine if the messagebuffer 545 contains a message (or information) to communicate to thesecond networked device 510. If the data communication module 540determines that the communication module 520 does not have an outgoingmessage to send to the second networked device 510, the datacommunication module 540 may resume operating in the mode in which thedata communication module 540 was operating when the incoming messagefrom the second networked device 510 arrived. Conversely, if the datacommunication module 540 determines that the communication module 520has an outgoing message to communicate to the second networked device510, the data communication module 540 may, for example, proceed tocommunicating the outgoing message to the second networked device 510.

The communication module 520 may have a MAC module 580 communicativelycoupled, for example, to the data communication module 540 andtransceiver module 530. The MAC module 580, in turn, may include anaccess time limiting module 590. The access time limiting module 590 maydetermine if there is enough time to communicate an outgoing message tothe second networked device 510 and maintain operation within the timingconstraints of the communication network 500. For example thecommunication network 500 may have a maximum time limit for which one ormore communicating networked devices may utilize the communicationmedium before allowing other networked devices an opportunity to accessthe communication medium.

The access time limiting module 590 may determine how long it will taketo communicate a particular outgoing message to the second networkeddevice 510. Such a time determination may include, for example,determining how long it will take the data communication module 540 totransmit the outgoing message to the second networked device 510 and howlong it will take the second networked device 510 to communicate areturn message to the data communication module 540. Having determinedthe communication time, the access time limiting module 590 may comparethe communication time to how much time the data communication module540 has left for utilizing the communication medium before system timingconstraints require the data communication module 540 to release controlof the communication medium for potential utilization by other networkeddevices.

If the access time limiting module 590 determines that there is notenough time remaining under the system time constraints to effectivelycommunicate the outgoing message to the second networked device 510, thedata communication module 540 may, for example, return to the mode ofoperation at which the data communication module 540 was operating whenthe incoming message arrived. Conversely, if the access time limitingmodule 590 determines that the data communication module 540 has time toeffectively communicate the outgoing message to the second networkeddevice 510, the data communication module 540 may proceed to communicatethe outgoing message to the second networked device 510.

The MAC module 580, discussed previously, may also include an accessmodule 585 that controls the communication module's 520 access to thecommunication medium. For example, in a communication network whereaccess to the communication medium is governed by a contention-basedmedium access protocol, the access module 585 may perform the necessaryprotocol steps to acquire access to and control of the communicationmedium.

In an exemplary scenario, the second networked device 510 may haveawakened from the sleep state of the power-save mode and gained accessto the communication medium using a contention-based medium accessprotocol, such as, for example, CSMA/CA. Having contended with othernetworked devices for access to the communication medium, and havingacquired control of the communication medium, the second networkeddevice 510 may then have transmitted the incoming message to thecommunication module 520. The communication module 520, havingdetermined that the second networked device 510 is a power-save deviceand is not currently in a sleep state, and having determined that thecommunication module 520 has an outgoing message for the power-savedevice, may, for example, utilize the communication medium tocommunicate the outgoing message to the second networked device 510without contending with other networked devices for access to thecommunication medium. The MAC module 580 may, for example, provide thismedium access functionality to the communication module 520.

Such operation may provide for communicating one or more outgoingmessages to the second networked device 510 in a time-efficient, andthus energy-efficient, manner. Though the previous example concernedcommunicating information to a power-save device, such exemplaryoperation should, by no means, limit the scope of various aspects of thepresent invention to methods and apparatus related to communicatinginformation with power-save devices.

The data communication module 540 is communicatively coupled to anoutgoing message queue 550 that contains a queue of messages to betransmitted over the communication medium. In particular scenarios, thedata communication module 540 may by-pass the outgoing message queue andutilize the transceiver module 530 to send an outgoing message over thecommunication medium. For example, when the communication module 520receives an incoming message, the communication module 520 (or deviceutilizing the communication module 520) may have had one or moreoutgoing messages in an outgoing message queue waiting for transmissionover the communication network. Rather than placing the outgoing messagedestined for the second networked device 510 in the outgoing messagequeue 550 to wait in line behind the messages already queued in theoutgoing message queue 550, the data communication module 540 may bypassone or more messages in the outgoing message queue.

Such exemplary operation provides for the outgoing message destined forthe second networked device 510 to be delivered to the second networkeddevice 510 in a more time-efficient manner. An exemplary advantageprovided by such operation is that in a power-save scenario where thesecond networked device 510 has emerged from a sleep state of apower-save mode to communicate with the communication module 520 (ordevice utilizing the communication module), the second networked device510 may complete its communications with the communication module 520and return to the sleep state of the power-save mode in a time-efficientmanner, thereby reducing unnecessary energy consumption by the secondnetworked device 510.

Though such operation may have advantages in communication networks thatinclude power-save devices, such efficient operation also has advantagesin communication networks that do not include power-save devices.Accordingly, the scope of various aspects of the present inventionshould, by no means, be limited to characteristics related tocommunicating information with power-save devices.

The outgoing message transmitted to the second networked device 510 maytake various forms. For example, in a scenario where the communicationmodule 520 is able to retrieve a buffered message destined for thesecond networked device 510 quickly enough to meet communication systemtiming constraints, the outgoing message may include the bufferedmessage. In an alternative example, the communication module 520 may notbe able to retrieve a buffered message destined for the second networkeddevice quickly enough to meet communication system timing constraints.In such a scenario, the communication module 520 may communicate analternate message (e.g., a null data message) to the second networkeddevice 510. Such a message may, for example, provide for maintainingcontrol over the communication medium and may also serve as anindication to the second networked device 510 that a message or streamof messages is forthcoming from the communication module 520. Note thatthe scope of various aspects of the present invention should not belimited to a particular form of outgoing message.

After transmitting a first outgoing message to the second networkeddevice 510, the communication module 520 may, for example, wait for asecond incoming message from the second networked device 510. Forexample, such a second incoming message may include an acknowledgmentfrom the second networked device 510 that the second networked device510 received the most recent message transmitted to the second networkeddevice 510 from the communication module 520. The second incomingmessage may, for example, also include a request from the secondnetworked device 510 for the communication module 520 to retransmit amessage. The communication module 520 may, for example, respond to sucha request, or the absence of a response message, by retransmitting theoutgoing message to the second networked device 510. Note that waitingfor a response message from the second networked device 510 is merely anexample and should, by no means, limit the scope of various aspects ofthe present invention to require such a response message.

After transmitting a first outgoing message to the second networkeddevice 510, and optionally waiting for and receiving a second incomingmessage from the second networked device 510, the data communicationmodule 540 may determine if the communication module 520 has additionalmessage information buffered that is addressed to the second networkeddevice 510. If the data communication module 540 determines that thecommunication module 520 (or device incorporating the communicationmodule 520) has no more messages for the second networked device 510,the data communication module 540 may, for example, return to the modeof operation at which the data communication module 540 was operatingwhen the original incoming message arrived.

Conversely, if the data communication module 540 determines that thecommunication module 520 has additional outgoing message information tosend to the second networked device 510, the data communication module540 may, for example, repeat some or all of the various operationsdescribed previously with regard to the first outgoing message.

Various modules of the communication module 520 may, for example, beincorporated into a single integrated circuit or incorporated intomultiple integrated circuits on a circuit card or multi-chip module.Various modules may include hardware, software, or combinations ofhardware and software. Various modules may also, for example, sharecomponents of the communication module 520, such as, for example, amicroprocessor, memory devices, bus infrastructure, clocks, etc.Accordingly, the scope of various aspects of the present inventionshould not be limited to particular arrangements and implementations ofthe various modules and sub-modules discussed.

In summary, a system and method are provided for efficientlycommunicating information between networked devices in a communicationnetwork. While the invention has been described with reference tocertain aspects and embodiments, it will be understood by those skilledin the art that various changes may be made and equivalents may besubstituted without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from itsscope. Therefore, it is intended that the invention not be limited tothe particular embodiment disclosed, but that the invention will includeall embodiments falling within the scope of the appended claims.

1. In a first networked device having the capability to communicate witha second networked device over a communication medium, the firstnetworked device having a message queue for outgoing messages, thesecond networked device having gained control over the communicationmedium by utilizing a contention-based medium access protocol afterexiting from an inactive state of a power-save mode, a method forcommunicating information to the second networked device, the methodcomprising: receiving an incoming message from the second networkeddevice indicating that the second networked device is ready to receiveinformation; transmitting a first outgoing message to the secondnetworked device prior to transmitting a queued message that was in themessage queue when the first networked device received the incomingmessage; and transmitting a second outgoing message to the secondnetworked device prior to transmitting the queued message.
 2. The methodof claim 1, wherein the incoming message is a data message comprising anindication that the second networked device has no more information tosend to the first networked device.
 3. The method of claim 1, furthercomprising: determining whether the second networked device has thecapability to operate in a power-save mode; determining whether thesecond networked device is currently operating in a sleep state of thepower-save mode; and performing the transmitting steps if the secondnetworked device has the capability to operate in a power-save mode, andthe second networked device is not currently operating in a sleep stateof the power-save mode.
 4. The method of claim 3, wherein thedetermining step comprises analyzing information in a database todetermine whether the second networked device has the capability tooperate in a power-save mode and whether the second networked device iscurrently operating in a sleep state of the power-save mode.
 5. Themethod of claim 1, wherein the first networked device performs at leastone of the transmitting steps without contending with other networkeddevices for access to the communication medium.
 6. The method of claim1, wherein the first networked device does not perform at least one ofthe transmitting steps if the first networked device determines thatcommunication of the respective outgoing message of the at least onetransmitting step will not complete within a time limit.
 7. The methodof claim 1, wherein the first outgoing message is a null data message.8. The method of claim 1, further comprising receiving a second incomingmessage between transmitting the first outgoing message and transmittingthe second outgoing message, the second incoming message acknowledgingreceipt of the first outgoing message by the second networked device. 9.A communication module for utilization in a first networked devicehaving the capability to communicate with a second networked device overa communication medium, the second networked device capable of gainingcontrol of the communication medium utilizing a contention-based mediumaccess protocol after exiting from a power-save mode, the communicationmodule comprising: a transceiver module that receives an incomingmessage from the second networked device indicating that the secondnetworked device is ready to receive information; an outgoing messagequeue for queuing outgoing messages for transmission over thecommunication medium; and a data communication module communicativelycoupled to the transceiver module and the outgoing message queue,wherein the data communication module may cause the transceiver moduleto: transmit a first outgoing message to the second networked deviceover the communication medium prior to transmitting a queued messagethat was in the message queue when the transceiver module received theincoming message; and transmit a second outgoing message to the secondnetworked device over the communication medium prior to transmitting thequeued message.
 10. The communication module of claim 9, wherein theincoming message is a data message comprising an indication that thesecond networked device has no more information to send to the firstnetworked device.
 11. The communication module of claim 9, furthercomprising a power-save determination module communicatively coupled tothe data communication module that determines whether the secondnetworked device is capable of operating in a power-save mode andwhether the second networked device is currently operating in a sleepstate of the power-save mode, and wherein the data communication modulecauses the transceiver module to transmit the first and second outgoingmessages if the second networked device has the capability to operate ina power-save mode and the second networked device is not currentlyoperating in a sleep state of the power-save mode.
 12. The communicationmodule of claim 11, further comprising a power-save information databasecommunicatively coupled to the power-save determination module, whereinthe power-save determination module analyzes information in thepower-save information database to determine whether the secondnetworked device has the capability to operate in a power-save mode andwhether the second networked device is currently operating in a sleepstate of the power-save mode.
 13. The communication module of claim 9,further comprising a medium access control module that allows thecommunication module to transmit at least one of the first and secondoutgoing messages without contending with other networked devices foraccess to the communication medium.
 14. The communication module ofclaim 9, further comprising a medium access control module that does notallow the communication module to transmit at least one of the outgoingmessages if the medium access control module determines that thecommunication of the at least one outgoing message to the secondnetworked device will not complete within a time limit.
 15. Thecommunication module of claim 9, wherein the first outgoing message is anull data message.
 16. The communication module of claim 9, wherein thetransceiver module receives a second incoming message betweentransmitting the first outgoing message and transmitting the secondoutgoing message, the second incoming message acknowledging receipt ofthe first outgoing message by the second networked device.
 17. Thecommunication module of claim 9, wherein the transceiver module,outgoing message queue, and data communication module are integrated ina single integrated circuit.
 18. In a first networked device having thecapability to communicate with a second networked device over acommunication medium, the first networked device having a message queuefor outgoing messages, a method for communicating information to thesecond networked device, the method comprising: receiving an incomingmessage from the second networked device indicating that the secondnetworked device is ready to receive information; transmitting a firstoutgoing message to the second networked device prior to transmitting atleast one message in the message queue; and transmitting a secondoutgoing message to the second networked device prior to transmittingthe at least one message in the message queue.
 19. The method of claim18, wherein the incoming message is a data message comprising anindication that the second networked device has no more information tosend to the first networked device.
 20. The method of claim 18, furthercomprising: determining whether the second networked device has thecapability to operate in a power-save mode; determining whether thesecond networked device is currently operating in a sleep state of thepower-save mode; and performing at least one of the transmitting stepsonly if the second networked device has the capability to operate in apower-save mode and the second networked device is currently not in asleep state of the power-save mode.
 21. The method of claim 18, whereinthe first networked device performs at least one of the transmittingsteps without contending with other networked devices for access to thecommunication medium.
 22. The method of claim 18, wherein the firstnetworked device does not transmit an outgoing message if communicationof the outgoing message will not complete within a time limit.
 23. Acommunication module for utilization in a first networked device havingthe capability to communicate with a second networked device over acommunication medium, the communication module comprising: a transceivermodule capable of receiving an incoming message from the secondnetworked device indicating that the second networked device is ready toreceive information; an outgoing message queue that queues outgoingmessages for transmission over the communication medium; and a datacommunication module communicatively coupled to the transceiver moduleand the outgoing message queue, wherein the data communication modulemay cause the transceiver module to: transmit a first outgoing messageto the second networked device over the communication medium prior totransmitting a queued message that was in the outgoing message queuewhen the transceiver module received the incoming message; and transmita second outgoing message to the second networked device over thecommunication medium prior to transmitting the queued message.
 24. Thecommunication module of claim 23, wherein the incoming message is a datamessage comprising an indication that the second networked device has nomore information to send to the first networked device.
 25. Thecommunication module of claim 23, further comprising a power-savedetermination module communicatively coupled to the data communicationmodule that determines whether the second networked device has thecapability to operate in a power-save mode and whether the secondnetworked device is currently operating in a sleep state of thepower-save mode; and wherein the data communication module causes thetransceiver module to transmit the first and second outgoing messages ifthe second networked device has the capability to operate in apower-save mode and is currently not operating in a sleep state of thepower-save mode.
 26. The communication module of claim 23, furthercomprising a medium access control module that allows the communicationmodule to transmit at least one of the first and second outgoingmessages without contending with other networked devices for access tothe communication medium during a time period in which access to thecommunication medium is generally governed by a contention-based mediumaccess protocol.
 27. The communication module of claim 23, furthercomprising a medium access control module that does not allow thecommunication module to transmit at least one of the outgoing messagesif the medium access control module determines that the communication ofthe at least one outgoing message to the second networked device willnot complete within a time limit.
 28. The communication module of claim23, wherein the transceiver module, outgoing message queue, and datacommunication module are integrated in a single integrated circuit.